Pressure regulator valves are commonly used to control the pressure of fluids supplied to various devices such as natural gas to gas fired appliances such as water heaters, furnaces and the like. One common type of pressure regulator employs a modulating valve controlled by a diaphragm responsive to fluid pressure, the diaphragm being biased by a spring which opposes the force exerted by the pressurized fluid and thus controls the action of the diaphragm. Other valves control the pressure of a fluid to maintain a pressure differential between that fluid and another fluid of reference pressure.
In all of these valves, the valves are either very complicated and have variable adjustments to select a predetermined pressure differential or are simple but have fixed components which cannot be altered or which must be altered by taking the valve apart and adjusting a component thereof.
The present invention overcomes the disadvantages of the prior art by providing a valve which controls the pressure of an input fluid by maintaining a pressure differential between that fluid and another fluid or fluids of reference pressure. It also acts as a bypass valve and allows the pressure differential to be adjusted external to the valve either mechanically or hydraulically from a remote source.
In the present invention, a piston divides an enclosed hollow body into first and second fluid-tight chambers. In one chamber is an input and an output orifice for a fluid whose pressure is to be regulated. An extension is connected to the piston in the first chamber for selectively opening and closing the output fluid orifice upon movement of the piston. A reference fluid input orifice and an adjustable pressure spring are formed in the second chamber in contact with the piston such that when the combined pressure of the reference fluid and the spring on one side of the piston exceeds the pressure of the input fluid on the other side of the piston, the output orifice closes, and when the pressure of the input fluid on one side of the piston exceeds the combined pressure of the reference fluid and the spring on the other side of the piston, the output orifice opens, thus bypassing the input fluid at a predetermined pressure. An elongated projection is threadedly inserted in an opening in the second chamber and is in contact with the spring, which contacts the piston, to vary the pressure of the spring on the piston and the pressure at which the output fluid orifice will open. Thus, when the elongated projection is mechanically threaded into or out of the second chamber, it increases or decreases the pressure on the piston through the spring to vary the pressure at which the output orifice in the first chamber will open.
In a first embodiment of the invention, the elongated projection also has an orifice therein and a second extension on the piston in the second chamber sealably extends partially into the hollow orifice. If it is desired to control the differential valve from a 10 remote location, a hydraulic fluid is coupled to the opening in the elongated projection and a fluid of desired pressure is supplied thereto which engages the second extension of the piston thus applying force to the extension, and the piston, to vary the point at which the output orifice in the first chamber will open. In at least one use of the invention, the remote location is at a connection to the bypass fluid from the outlet orifice. By connecting the outlet fluid pressure to the end surface of the second extension, the end area of the two extensions are effectively pressure balanced.
Thus it is an object of the present invention to provide a valve which controls the pressure of an input fluid by maintaining a pressure differential between that fluid and another fluid of reference pressure.
It is also an object of the present invention to provide a valve which acts as a bypass valve when the input fluid exceeds a reference pressure.
It is another important object of the present invention to provide a valve in which the pressure differential can be adjusted from the outside of the valve either mechanically or remotely by varying a hydraulic pressure to the valve.
It is also an object of the present invention to provide a differential pressure valve in which a reference pressure is supplied by both a reference fluid and a spring acting on a piston such that the pressure can be varied by externally varying the pressure applied to the spring which varies the pressure applied to the piston.
In an alternative embodiment, it is a more detailed object of the present invention to simplify the construction of the fluid connection between the bypass fluid and the end surface of the second connection and to improve the overall accuracy of the pressure balancing of the end areas of the two extensions.